The experimental article focuses on the flow characteristics and acoustic features of a jet issuing from a Convergent Divergent (C-D) nozzle with a cruciform (cross-shaped) cross-section. The design Mach number is 1.5. The cruciform nozzle has an equivalent exit diameter of 5.42 mm, and its features are compared with the equivalent circular and square nozzles. The operating Nozzle Pressure Ratio (NPR) is varied from 2 to 6. The pitot probe and microphone, in conjunction with data acquisition instruments, provide the total pressure and acoustic measurements of the jet flow. The cruciform jet exhibits a shorter supersonic core length compared to both the circular and square jets for all operating NPRs. Compared to circular and square jets, the cruciform jet has a maximum Overall Sound Pressure Level (OASPL) reduction of 7.06 dB and 7.73 dB at NPR 5. The screech is suppressed and is only discernible at NPR 5 in the cruciform jets, whereas it exists from NPR 3 to 6 in the other two jets. The higher screech amplitudes are localized to lower emission angles from 45° to 75°. Together, the OASPL, and screech are suppressed in cruciform jets.
De GregorioF. Free compressible jet investigation. Exp Fluid2014; 55(3): 1693.
2.
MundayDCuppolettiDPerrinoM, et al.Supersonic turbojet noise reduction. Int J Aeroacoustics2013; 12(3): 215–243.
3.
KuoC-WVeltinJMcLaughlinDK. Acoustic measurements of models of military style supersonic nozzle jets. Chin J Aeronaut2014; 27(1): 23–33.
4.
KannanBTSsheshanPSenthilkumarS. Large eddy simulation of isothermal cruciform jet flow: preliminary results. Perspect Sci2016; 8: 10–12.
5.
KannanBTSenthilkumarS. Numerical simulation of isothermal cruciform jet flow. In: SahaAKDasDSrivastavaR, et al. (eds). Lecture Notes in Mechanical Engineering. Springer India, 2017, pp. 595–604.
6.
QuinnWRMarstersGF. Upstream influence on turbulent jet flows from cruciform nozzles. Aeronaut J1985; 89(882): 55–58.
7.
QuinnWRAzadM. Mean flow and turbulence measurements in a turbulent free cruciform jet. Flow Turbul Combust2013; 91(4): 773–804.
8.
FujitaSOsakaH. Effect of aspect ratios on potential core length for cruciform jet. Exp Therm Fluid Sci1992; 5(3): 332–337.
9.
Arun KumarPRathakrishnanE. Scaling law for supersonic core length in circular and elliptic free jets. Phys Fluids2021; 33(5): 051707.
10.
AkramSArun KumarPRathakrishnanE. Effect of tab parameters on the near-field mixing characteristics of a mach 1.5 elliptic jet. Phys Fluids2021; 33(3): 036114.
11.
Arun KumarPAileniMRathakrishnanE. Impact of tab location relative to the nozzle exit on the shock structure of a supersonic jet. Phys Fluids2019; 31(7): 076104.
12.
HeebNGutmarkELiuJ, et al.Fluidically enhanced chevrons for supersonic jet noise reduction. AIAA J2014; 52(4): 799–809.
13.
HeebNGutmarkEKailasanathK. Investigation of chevron penetration’s effect on supersonic jet noise reduction. AIAA J2016; 54(3): 1135–1139.
14.
MeslemANastaseI. Cross and clover shaped orifice jets analysis at low reynolds number. Therm Sci2015; 19(6): 2139–2150.
15.
AnurekaRSrinivasanK. Passive control of pipe-jet noise using trailing-edge castellations. Appl Acoust2020; 170: 107516.
16.
TamCKWShenHRamanG. Screech tones of supersonic jets from bevelled rectangular nozzles. AIAA J1997; 35(7): 1119–1125.
17.
BogadiSSridharBTN. Acoustic characteristics of supersonic rectangular jets issuing from nozzles with diagonal expansion ramps. J Braz Soc Mech Sci Eng2021; 43(12): 572.
18.
VinayCAravindh KumarSMRathakrishnanE. Mixing characteristics of underexpanded elliptic sonic jets from orifice and nozzle. J Propul Power2015; 31(2): 496–504.
19.
VinayCAravindh KumarSMRathakrishnanE. Aspect ratio effect on elliptical sonic jet mixing. Aeronaut J2016; 120: 1197–1214.
20.
MillerRSMadniaCKGiviP. Numerical simulation of non-circular jets. Comput Fluids1995; 24(1): 1–25.
21.
Rajesh KumarSKannanBT. Acoustic measurements of compressible jet flow from a pipe nozzle with clover cross-section. In: 2023 Eighth International Conference on Science Technology Engineering and Mathematics (ICONSTEM), 6 April 2023. IEEE, pp. 1–4.
22.
ChenNYuH. Mechanism of axis switching in low aspect-ratio rectangular jets. Comput Math Appl2014; 67(2): 437–444.
23.
RathakrishnanE. Applied gas dynamics. Wiley, 2019.
24.
TamCKW. Supersonic jet noise. Annu Rev Fluid Mech1995; 27: 17–43.
25.
TamCKWSeinerJMYuJC. Proposed relationship between broadband shock associated noise and screech tones. J Sound Vib1986; 110(2): 309–321.
26.
JothiTJSSrinivasanK. Turbulent mixing noise from underexpanded non-circular slot jets. Acta Acust United Acust2013; 99(4): 514–523.
27.
RamanG. Advances in understanding supersonic jet screech: review and prespective. Prog Aero Sci1998; 34: 45–106.
28.
RamanG. Cessation of screech in underexpanded jets. J Fluid Mech1997; 336: 69–90.
29.
TamCKWParrishSAViswanathanK. The harmonics of jet screech tones. In: 19th AIAA/CEAS Aeroacoustics Conference. American Institute of Aeronautics and Astronautics, 2013, p. 89.
30.
AokiTKweonY-HMiyazatoY, et al.An experimental study of the nozzle lip thickness effect on supersonic jet screech tones. J Mech Sci Technol2006; 20: 522–532.
31.
JothiTJSSrinivasanK. Role of initial conditions on noise from underexpanded pipe jets. Phys Fluids2009; 21(6): 066103.
32.
JothiTJSSrinivasanK. Surface roughness effects on noise from pipe jets. J Sound Vib2013; 332(4): 839–849.
33.
BellidegaKCDhamanekarASrinivasanK. Acoustic characteristics of annular jets. In: INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, Melbourne, Australia, November 16-19, 2014, 2014, pp. 1–8.
34.
WilliamsJEFKemptonAJ. The noise from the large-scale structure of a jet. J Fluid Mech1978; 84(4): 673–694.
35.
Rajesh KumarSNishchaySKannanBT. Effect of aspect ratio on mean flow characteristics of cruciform orifice jet. Aircraft Eng Aero Technol2024; 96(1): 144–150.
36.
SushilSKGargMNarayananS. Estimation of the lower cut-off frequency of an anechoic chamber: an empirical approach. Int J Aeroacoustics2020; 19(1-2): 57–72.
37.
WhiteFM. Fluid mechanics. 8th ed.. McGraw Hill Education India Private Limited, 2016, p. 362.
